Device for supporting and adjusting matrix-bands



I. BORKIN. nEvlcE rox SUPPORTING AND AnJusTlNG MATmx BANDS.

APPLICATION FILED MAR. 28. 1919. ,1,35966 5, Patented Nov. 23, 1920.

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f y l h UNITED STATES ISRAEL BORKIN, 0F NEW YORK, N. Y.

DEVICE FOR SUPPORTING AND ADJUSTING- MATRIX-BANDS.

y Speciiication of Letters Patent.

Application filed March 28, 1919. Serial No. 285,867.

i 1o all whom it may concern Be it known` that T, lsRAnL BORKIN, a citizen or the United States, residing at N ew York, in the county o1" New York, and State of New York, have invented certain new and useful improvements in pevices for Supporting and Adjusting Matrix Bands, oi which the following is a specication.

This invention relates to devices for supporting and adjusting matrix bands and the objects oi the invention are to provide simple and effective means -for this purpose, which can be readily adjusted and which can be made relatively inexpensively.

These objects T have accomplished by constructing a holder for the matrix band embodying an elongated support includingtwo relatively slidable parts, a loop at one end of one of the parts, i'or receiving parts of the band intermediate its bight and free ends, and a keeper on the other part, for receivinof the ifree ends or the band; and also by constructing the Vholder so that it embodies, similarly to the holder oi my application Serial No. 223,294, of which this application is a continuation in part, a tubular stock or handle carrying the keeper, a

tightening rod slidingly engaged in the tubular stock and carrying the loop, and means for adjusting said band-tightening rod.

Other features and the details of coin struction will be. made clear as thespecid cation proceeds, attention being new invited to the accompanying drawing, wherein I have illustrated the invention embodied in a practical commercial form.

In said drawing, Figure 1 is a top plan view ol the device with the matrix band not yet engaged about a toothgFig. 2 is a side elevation; Fig. 3 is a view similar to Fig. 2, but showing the band engaged about a tooth; and Fig. 4; is a fragmentary view showing a part ot the device in bottom plan.

The elongated support includes the two relatively slidable parts and 12. The numeral 5 designates the stock or handle. of the device which is oi tubular construction, internally screw-threaded at one end at6, and provided on one side, near its opposite end with a keeper or holder for one end of the matrix band 7. This keeper is here provided by an arch or spaced ring 8, formed on one side of the stock, in which is mount ed a clamp screw 9, for clamping the doubled end of the band in the passage provided beneath such ring. This passage lies close to the body of the stock and isy disposed substantially longitudinally thereof so that the ends of theband lie flat against the stock, and do not protrude or stand out. A firm grip on the band is assured by'cupping the bottom of the passage beneath the point of the clamping screw as indicated at 11, and by the location of this depression intermediate the endsk of the passage the deflection of the band will be localized and thus the band will not be bent to such an extent as to cause the end of the band, if it extends beyond the keeper, from standing out at an angle from the stock.

The band-tightening member comprises a rod 12, the shank of which is slidingly en-` gaged in the bore of the stock and which carries aV head 13, formed with a slotted opening 14 through which the bight of the band is passed. This rod-is held against turning in the stock by a sliding pin-and slot connection therewith, comprising an outstanding pin or lug 15 on the rod `workinoin a longitudinal slot 16 in the stock. This pin-and-slot connection may also be utilized to limit the longitudinal shifting movement of the band-tightening member.

The adjusting means for the band-tightening member consists, in the present disclosure, of a screw rod 17 engaged in the threaded end of the stock, vhaving an eX- posed finger hold or operating head 18 and projecting' into the bore far enough to bear upon the rear end oit' the rod 12.

It will be apparent that by simply turning the linger hold 18 the matrix band may be tightened or loosened, as desired. The adjustable keeper permits the band to be readily lengthened or shortened for making larger or smaller loops, as required and when adjusted to the proper length the band is securely held. Constructed as described, the movable elements of the device are for the most part housed within the tubular stock and there are no exposed projecting parts liable to cause injury in the use of the device.

The head 13 also preferably carries a cross-piece 19 spaced' away from the'head, and which may be formed as a loop as indicated. Such loop 19 has a lip 2O overhanging the slotted opening 14;. This arrangement facilitates quick mounting and remounting of a matrix band, without dan- Patented Nov. 23, 1920.

ger of bending sharply or otherwise injuring the same in advancing the `tree ends et r the band beyond the opening 14 and toward and inte the keeper. v a

The head 13, further, is preterablymade convex' as indicated at 21 in Fig.` 1, that is,

across the hea-d and between the feet of the side-legs et slotted, opening 14; as I have discovered that by such a construction the lifeoirl a `band is much increased and cracking of the band is delayed atthe points where it changes directien across its flat v between opening 141- and keeper 8.

I, claimt- 1. A device ot' the character described, a matrix band, a tubular stock provided with a longitudinally arranged keel er ter the matrix band in one side thereof and extending` longitudinally of the stock, means for sccnringthe band in said keeper, a band-V tightening rod slidably engaged in the stock and provided at one end thereoi with 1 transverse opening` 'for receiving the band and means or'shiitting the rod in the tnbnlar stock.

In a device ot the character described, a `tubular stock having a depression in one l' side thereotand a keeper overlying said depression, ai-matrix band engaged beneath tlre keeper, a clamp screw adjustably engaged in said keeper above the depression for clamping the band therein, a bandtight- "El e'ningrod slidably engaged in the tubular opposite end, an' operating screw enga-ged with the screw-threaded portion et the stock and extending into the bore of the stock, a band-tightening rod having a shank portion disposed in the bore and engagedby the end of the operating screw and an outer headed portion provided with a transverse slotte receive a matrix band, a matrix band engaged in said slot and in the keeper loop ateresaid, and means :t'or securing the band in the keeper, the lasteinentioned means including a depression in the stock below the keeper and a tightening screw threaded through the keeper and spirally adjustable toward the depression.

a. In a Vdevice ofthe character described, an elongated support including two re1atively Vslidable parts, a transverse opening at one end oat one of the parts, a matrix band adapted to be `bowed and to have its tree ends passed .through the transverse opening, aV keeper lfor receiving said' free ends of the band on the other part near the end thereof adjacent to the band carrying end of the first part, and a second opening en the iirst part, between the lirst opening and the keeper, and throughivvhich the free ends or the band are guided and pass `for entering the keeper.

In a device of the character described, an elongated support including two relatively slidable parts, one otsaid parts having a transverse opening adjacent one end thereof, a matrix bandadapted to be bowed and to have its free endspassed through the transverse opening, a keeper for receiving said free ends of the band on the other part near the end thereof adjacent to the bandv carrying end of the rst part, and a cross-piece spaced from and carried by the irst part between Vthe transverse opening and the keeper, and under which the free ends of the band are guided and pass for entering the keeper. A

(i. The device defined in claim 5, wherein said eross-pieceoverlaps but liesabove the transverse opening.

i. The device defined in claim il, wherein said second opening is arranged at anV angle to the rst opening and is provided at its night with a lip overhanging the first opening.' j, Y

In testimony whereof I aflix my sionature.

ISRAEL noiKrN. 

